Matrix-embedded metamaterial coating, coated article having matrix-embedded metamaterial coating, and/or method of making the same

ABSTRACT

Certain example embodiments of this invention relate to coated articles having a metamaterial-inclusive layer, coatings having a metamaterial-inclusive layer, and/or methods of making the same. Metamaterial-inclusive coatings may be used, for example, in low-emissivity applications, providing for more true color rendering, low angular color dependence, and/or high light-to-solar gain. The metamaterial material may be a noble metal or other material, and the layer may be made to self-assemble by virtue of surface tensions associated with the noble metal or other material, and the material selected for use as a matrix. An Ag-based metamaterial layer may be provided below a plurality (e.g., 2, 3, or more) continuous and uninterrupted layers comprising Ag in certain example embodiments. In certain example embodiments, barrier layers comprising TiZrOx may be provided between adjacent layers comprising Ag, as a lower-most layer in a low-E coating, and/or as an upper-most layer in a low-E coating.

TECHNICAL FIELD

Certain example embodiments of this invention relate to coated articles,coatings used in connection with coated articles, and methods of makingthe same. More particularly, certain example embodiments of thisinvention relate to coated articles having a metamaterial-inclusivelayer, coatings having a metamaterial-inclusive layer, and/or methods ofmaking the same. Metamaterial-inclusive coatings may be used, forexample, in low-emissivity applications, providing for more true colorrendering, low angular color dependence, and/or high light-to-solargain.

BACKGROUND AND SUMMARY

Coated articles are known in the art. Coated articles have been used,for example, in window applications such as insulating glass (IG) windowunits, vehicle windows, and/or the like.

In certain situations, designers of coated articles often strive for acombination of desirable visible transmission, desirable color values,high light-to-solar gain (LSG, which is equal to visible transmission(T_(vis)) divided by solar heat gain coefficient (SHGC)) values,low-emissivity (or low-emittance), low SHGC values, and low sheetresistance (10. High visible transmission, for example, may permitcoated articles to be more desirable in certain window applications.Low-emissivity (low-E), low SHGC, high LSG, and low sheet resistancecharacteristics, for example, permit such coated articles to blocksignificant amounts of IR radiation from passing through the article.For example, by reflecting IR radiation, it is possible to reduceundesirable heating of vehicle or building interiors.

When light passes through a coated article, however, the perceived coloris not always “true” to the original, e.g., because the incidentexternal light is modified by the film or substrate of the window. Thecolor change oftentimes is angularly dependent. Indeed, in conventionalcoated articles that include low-E coatings, angular color oftentimes issacrificed to obtain high LSG.

It will be appreciated that it oftentimes would be desirable to helpensure that transmitted color rendering is true, and/or to reduce theseverity of or possibly even completely eliminate the tradeoff betweenangular coloration and LSG. Certain example embodiments address theseand/or other concerns.

The field of “metamaterials” is an emerging technology area and is seenas a way to enable certain new technologies. Some efforts have been madeto use such materials in a variety of applications such as, for example,in satellite, automotive, aerospace, and medical applications.Metamaterials also have started to show some promise in the area ofoptical control.

Unfortunately, however, the use of metamaterials in optical controlcoatings and the like has been plagued by losses related to undesirablesurface plasmon resonances or polaritons and can lead to thermal gain.In this regard, and as is known to those skilled in the art, theresonance wavelength is the wavelength at which the metamaterialexhibits surface plasmon resonance. It is typically accompanied by a dipin transmittance and an increase of reflectivity.

Certain example embodiments have been able to overcome these problemsassociated with the use of metamaterials in optical control coatings.For example, certain example embodiments use a combination of a highindex dielectric and a noble metal, which together create a desirableresonance. In this regard, modelling data has indicated a resonance inthe near infrared (NIR) spectrum (e.g., from about 700-1400 nm) issufficient to control angular coloration, as well as improvement in LSG.Metamaterials thus may be used in low-E coatings, and layers may bedeposited using sputtering or other technologies.

It will be appreciated that the metamaterial-inclusive layers describedherein include discontinuous features with individual length scaleslonger than individual molecules and atoms but shorter than thewavelength of light (typically in the 10-300 nm range), and having asynthetic structure that exhibits properties not usually found innatural materials. In certain example embodiments, layers comprisingdiscontinuous deposits of sub-wavelength size metal islands areprovided, with the sub-wavelength size being for example less than theshortest visible wavelength (e.g., less than about 380 nm). It will beappreciated that the properties not usually found in natural materialsthat pertain to certain example embodiments may include, for example,the desirable resonances and angular coloration discussed herein,creation of colored transmission to simulate a tinted substrate (e.g.,consistently across a wide range of viewing angles), creation of coloror visual acuity enhancing effects such as might be used with sunglasseswhere particular visible ranges of wavelengths are selectively absorbed,etc.

In certain example embodiments, a method of making a coated articlecomprising a low-E coating supported by a glass substrate is provided.The method comprises: forming a first matrix layer comprising a matrixmaterial, directly or indirectly on the substrate; forming a donor layercomprising Ag over and contacting the first matrix layer; followingformation of the donor layer, forming a second matrix layer comprisingthe matrix material over and contacting the donor layer, wherein thefirst and second matrix layers have thicknesses differing from oneanother by no more than 20%; heat treating the coated article with atleast the first and second matrix layers and the donor layer thereon tocause the Ag in the donor layer to self-assemble into a discontinuouscollection of formations distributed in the matrix material in forming ametamaterial inclusive layer that emits resonances in a desiredwavelength range based at least in part on the formations locatedtherein; and incorporating the metamaterial inclusive layer into thelow-E coating.

In certain example embodiments, a method of making a coated articlecomprising a low-E coating supported by a glass substrate is provided.The method comprises: forming a first matrix layer comprising a matrixmaterial, directly or indirectly on the substrate; forming a continuousand uninterrupted donor layer over and contacting the first matrixlayer, with the donor layer comprising one or more source material(s)selected from the group consisting of: Ag, Al, Au, AZO, Be, C, Cr, Cu,ITO, Ni, Pd, Pt, RuO2, Ti, and W; and following formation of the donorlayer, forming a second matrix layer comprising the matrix material overand contacting the donor layer, wherein the first and second matrixlayers have thicknesses differing from one another by no more than 20%.The coated article with at least the first and second matrix layers andthe donor layer thereon are heat treatable to cause the sourcematerial(s) in the donor layer to self-assemble into a synthetic layercomprising a discontinuous collection of formations distributed in thematrix material, with the formations having a major distance no largerthan 300 nm, and with the synthetic layer having resonance in afrequency range suitable for the low-E coating.

In certain example embodiments, a method of making a coated articlecomprising a low-E coating supported by a glass substrate is provided.The method comprises: having a plurality of layers formed on thesubstrate, the layers including: (a) a first matrix layer comprising amatrix material, directly or indirectly on the substrate, (b) a donorlayer comprising Ag over and contacting the first matrix layer, and (c)a second matrix layer comprising the matrix material over and contactingthe donor layer, wherein the first and second matrix layers havethicknesses differing from one another by no more than 20%; and heattreating the coated article with at least the first and second matrixlayers and the donor layer thereon to cause the Ag in the donor layer toself-assemble into a discontinuous collection of formations distributedin the matrix material in forming a metamaterial inclusive layer, withthe metamaterial inclusive layer having resonance in a selectedfrequency range suitable for the low-E coating.

In certain example embodiments, there is provided an intermediatearticle, comprising a glass substrate. A first matrix layer comprising amatrix material is located directly or indirectly on the substrate. Adonor layer comprising Ag is located over and contacting the firstmatrix layer. A second matrix layer comprising the matrix material islocated over and contacting the donor layer. The first and second matrixlayers have thicknesses differing from one another by no more than 20%.The intermediate article is heat treatable with at least the first andsecond matrix layers and the donor layer thereon to cause the Ag in thedonor layer to self-assemble into a discontinuous collection offormations distributed in the matrix material in forming a metamaterialinclusive layer that emits resonances in a desired wavelength rangebased at least in part on the formations located therein.

The features, aspects, advantages, and example embodiments describedherein may be combined to realize yet further embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages may be better and morecompletely understood by reference to the following detailed descriptionof exemplary illustrative embodiments in conjunction with the drawings,of which:

FIG. 1 is a cross-sectional view of an example layer stack having threeAg-inclusive layers and one metamaterial-inclusive layer, in accordancewith certain example embodiments;

FIG. 2a is a graph plotting the transmission, film-side reflectance, andglass-side reflectance against wavelength for the FIG. 1 example coatedarticle;

FIG. 2b is a graph plotting glass-side a* and b* values against viewingangle for the FIG. 1 example coated article;

FIGS. 3a-3c are cross-sectional views of example triple silver low-Ecoatings that have been tuned to provide improved angular coloration andhigh LSG;

FIG. 4 is a graph plotting C vs. LSG values for the example coatedarticles shown in and described in connection with FIGS. 1 and 3 a-3 c;

FIG. 5a is a graph plotting the transmission, film-side reflectance, andglass-side reflectance against wavelength for a sample including asingle metamaterial-inclusive layer on a glass substrate, and FIG. 5bplots the glass-side a* and b* values against angle for that sample;

FIG. 6a is a graph plotting the transmission, film-side reflectance, andglass-side reflectance against wavelength for a sample including asingle Ag-inclusive layer (a layer comprising or consisting essentiallyof Ag) on a glass substrate, and FIG. 6b plots the glass-side a* and b*values against angle for that sample;

FIG. 7a is a graph plotting the transmission, film-side reflectance, andglass-side reflectance against wavelength for a sample including asingle Ag-inclusive layer (a layer comprising or consisting essentiallyof Ag) supported by a single metamaterial layer on a glass substrate,and FIG. 7b plots the glass-side a* and b* values against angle for thatsample;

FIGS. 8a and 8b correspond to FIGS. 6a and 6b , except that additionaldielectric layers are provided for optical tuning;

FIGS. 9a and 9b correspond to FIGS. 7a and 7b , except that additionaldielectric layers are provided for optical tuning;

FIGS. 10a-10b show the resonance intensity and resonance wavelength fordifferent radius, thickness, and interparticle distance combinations forcolumnar Ag metamaterial formations in a silicon oxide matrix;

FIG. 11 shows the resonance wavelength for different radius, thickness,and interparticle distance combinations for columnar Ag metamaterialformations in a niobium oxide matrix;

FIGS. 12a-12b show the resonance intensity and resonance wavelength fordifferent radius, thickness, and interparticle distance combinations forcolumnar Au metamaterial formations in a silicon oxide matrix;

FIGS. 13a-13b show the resonance intensity and resonance wavelength fordifferent radius, thickness, and interparticle distance combinations forcolumnar Cu metamaterial formations in a silicon oxide matrix;

FIGS. 14a-14b show the resonance intensity and resonance wavelength fordifferent radius, thickness, and interparticle distance combinations forcolumnar TiN metamaterial formations in a silicon oxide matrix;

FIG. 15 shows the resonance wavelength for different radius, thickness,and interparticle distance combinations for ellipsoidal Ag metamaterialformations in a silicon oxide matrix;

FIG. 16 is a graph showing the plasmon resonance observed in thecalculated absorption from optical measurements for different heattreatment temperature and times for a first layer stack;

FIGS. 17a-17c are TEM images showing the evolution of ametamaterial-inclusive layer for the first layer stack, when heattreated at 650 degrees C.;

FIG. 18 is a graph showing the plasmon resonance observed in thecalculated absorption from optical measurements for different heattreatment temperature and times for a second layer stack; and

FIGS. 19a-19c are TEM images showing the evolution of ametamaterial-inclusive layer for the second layer stack, when heattreated at 650 degrees C.

DETAILED DESCRIPTION

Certain example embodiments relate to coated articles having ametamaterial-inclusive layer, coatings having a metamaterial-inclusivelayer, and/or methods of making the same. Metamaterial-inclusivecoatings may be used, for example, in low-emissivity applications,providing for more true color rendering, low angular color dependence,and/or high light-to-solar gain. As indicated above, it would bedesirable in many instances to have transmitted color rendering that istrue, e.g., such that incident external light is not perceived as havingbeen modified by the film and/or substrate of the window. It is possibleto obtain this performance with the FIG. 1 coated article, in certainexample embodiments. That is, FIG. 1 is a cross-sectional view of anexample layer stack 102 supported by a glass substrate 100 and havingthree Ag-inclusive layers 112 a-112 c and one metamaterial-inclusivelayer 106, in accordance with certain example embodiments. As shown inFIG. 1, the metamaterial-inclusive layer 106 is the lowest Ag-containinglayer in the triple-silver layer stack. That is, themetamaterial-inclusive layer 106 is closer to the substrate 100 than iseach of Ag-inclusive layers 112 a-112 c. In different exampleembodiments, however, the metamaterial-inclusive layer 106 may beprovided elsewhere. For instance, it may be provided between or above agiven Ag-containing sub-stack.

A first barrier layer 104 is provided between the glass substrate 100and the metamaterial-inclusive layer 106. This barrier layer 104 mayinclude titanium oxide and/or zirconium in certain example embodiments.The inclusion of a barrier layer 104 or the like may be advantageous interms of reducing the likelihood of sodium migration from the substrateinto the layer stack 102 (e.g., where it could damage layers includingthe Ag-inclusive layers 112 a-112 c, the metamaterial-inclusive layer106, etc.), especially because the high temperatures that may be used inthe formation of the metamaterial-inclusive layer 106 (e.g., as setforth in greater detail below), heat treatment (including heatstrengthening and/or thermal tempering), etc., may be likely to promotesuch sodium migration.

One or more dielectric layers (not shown) also may be interposed betweenthe substrate 100 and the metamaterial-inclusive layer 106. Thesedielectric layers may be silicon-inclusive layers (e.g., layerscomprising silicon oxide, silicon nitride, silicon oxynitride, etc.)that optionally may also include aluminum, layers comprising titaniumoxide, layers comprising tin oxide, etc.

FIG. 1 may be thought of as including sub-layer stacks above themetamaterial-inclusive layer 106, with a single sub-layer stackrepeating once for each silver-inclusive layer in the overall stack 102.As will be appreciated from FIG. 1, each sub-layer stack includes abarrier layer, a lower contact layer, a layer comprising Ag, and anupper contact layer. In the FIG. 1 example embodiment, the barrierlayers 108 a-108 c comprising titanium and/or zirconium, and may beoxided. Thus, as shown in FIG. 1, the barrier layers 108 a-108 c eachcomprise TiZrOx (although TiOx, ZrOx, and/or the like may be used indifferent example embodiments). In the FIG. 1 example embodiment, thelower contact layers 110 a-110 c comprising zinc oxide. The lowercontact layers 110 a-110 c may further include tin and/or aluminum incertain example embodiments, and they may provide smooth layers on whichthe respective layers comprising Ag 112 a-112 c can grow directly. Inthe FIG. 1 example embodiment, the upper contact layers 114 a-114 c arein direct contact with the layers comprising Ag 112 a-112 c and mayinclude, for example, Ni, Cr, Ti, and/or an oxide thereof. For instance,as shown in FIG. 1, the upper contact layers 114 a-114 c each compriseNiTiNbO (although NiCrOx, NiTiOx, and/or the like may be used indifferent example embodiments). An overcoat layer 116 may be provided tohelp protect the layer stack. The overcoat layer 116 may includezirconium in certain example embodiments. Optionally, certain exampleembodiments may include additional overcoat layers including, forexample, layers comprising silicon (e.g., silicon oxide, siliconnitride, or silicon oxynitride), etc. In certain example embodiments,the barrier layer 104 and the overcoat layer 116 may be formed from thesame or different materials.

In certain example embodiments, the thicknesses of the some or all ofthe contact layers 110 a-110 c may be substantially the same (e.g.,varying by no more than 15% of one another, more preferably varying byno more than 10% of one another). In certain example embodiments, thethicknesses of the some or all of the layers comprising Ag 112 a-112 cmay be substantially the same (e.g., varying by no more than 15% of oneanother, more preferably varying by no more than 10% of one another). Incertain example embodiments, the thicknesses of the innermost andoutermost layers may be substantially the same (e.g., varying by no morethan 15% of one another, more preferably varying by no more than 10% ofone another).

The following table provides information about the layers in the FIG. 1example coated article.

More Preferred Preferred Example Layer Thickness Thickness ThicknessGlass (100) (nm) (nm) (nm) TiZrOx (104) 20-100 30-50  39 Metamaterial(106) 5-25 5-15 13 TiZrOx (108a) 10-120 30-100 64 ZnO (110a) 1-20 3-15 4Ag (112a) 5-50 10-25  15 NiTiNbO (114a) 1-20 1-10 3 TiZrOx (108b) 10-12030-100 60 ZnO (110b) 1-20 3-15 4 Ag (112b) 5-50 10-25  16 NiTiNbO (114b)10-120 30-100 47 TiZrOx (108c) 1-20 3-15 8 ZnO (110c) 1-20 3-15 4 Ag(112c) 5-50 10-25  17 NiTiNbO (114c) 1-20 1-10 3 TiZrOx (116) 20-10030-50  31

Optical properties of the FIG. 1 example coated article are provided inFIG. 2a . That is, FIG. 2a is a graph plotting the transmission,film-side reflectance, and glass-side reflectance against wavelength forthe FIG. 1 example coated article. The following table summarizes theseand other optical properties, as well as thermal performance.

Monolithic Optics T Y (%) 76.8 (Ill. ‘C’, 2 deg obs) a* −5.00 b* −1.34Rg Y (%) 2.7 a* −1.06 b* −0.58 Rf Y (%) 2.0 a* 4.04 b* −0.55 A[vis](100-TT-Rf) 21.2 Double Glazing/IGU Optics T Y (%) 69.5 (Ill. ‘C’, 2 degobs) a* −5.47 b* −1.17 Rg Y (%) 7.5 a* −3.45 b* −1.45 Rf Y (%) 9.8 a*0.77 b* −0.66 Normal Emissivity (EN) 0.02 Double Glazing/IGU Tvis (%)69.5 NFRC-2001 Thermal Tsol (%) 25.4 Performance Rsol (%) 46.1 Asol (%)28.5 Uval 0.253 SHGC 27.5 LSG(25) 2.53In these samples, the IG units included two 3 mm substrates that were 12mm apart from one another. All samples were on clear glass.

The small a* and b* values are indicative of an excellent transmittedcolor and, as can be seen, the LSG is still high. With respect to a* andb*, the coloration is generally neutral and, in any event, differentfrom the yellow-green color shift that oftentimes accompanies solarcontrol coatings. It thus can be seen that certain example embodimentsadvantageously provide for excellent, neutral transmitted color, whichmaintaining a high LSG, in connection with a layer stack that has threeAg-inclusive layers and one metamaterial layer. The transmitted colorrendering thus is true. In some instances, it is possible to avoid anyyellow-green color shift, even though other color shifts might occur.

Also as indicated above, it would be desirable in many instances toreduce the severity of or possibly even completely eliminate thetradeoff between angular coloration and LSG. That is, it would bedesirable to avoid having to sacrifice angular coloration in order toobtain high LSG values. It also is possible to obtain this performancewith the FIG. 1 coated article, in certain example embodiments.

FIG. 2b is a graph plotting glass-side a* and b* values against viewingangle for the FIG. 1 example coated article. As can be seen from FIG. 2b, the glass-side a* and b* values are fairly uniform over the entirerange from 0-90 degrees. Preferably, the glass-side a* and b* valuesvary by no more than 2 over this range, more preferably no more than1.75, still more preferably no more than 1.5, and sometimes no more than1.0. In certain example embodiments, the glass-side a* and b* values arebetween 0 and −2 for substantially all angles between 0 and 90 degrees.It also can be seen from the FIG. 2b graph that glass-side a* and b*values each are very uniform in the 30-90 degree range and in each ofthe 30-60 and 60-90 degree ranges.

Performance of the FIG. 1 example coated article has been tested againstother more conventional triple silver low-E coatings that have beentuned. In this regard, FIGS. 3a-3c are cross-sectional views of exampletriple silver low-E coatings that have been tuned to provide improvedangular coloration and high LSG. The following tables provideinformation about the layers in the example coated articles shown inFIGS. 3a -3 c.

The FIG. 3a layer stack 302 a, somewhat similar to the FIG. 1 layerstack 102, includes a sub-layer stack for each silver-inclusive layer inthe overall stack 102. As will be appreciated from FIG. 1, eachsub-layer stack includes a barrier layer, a lower contact layer, a layercomprising Ag, and an upper contact layer. Furthermore, like the FIG. 1example, the lower contact layers 110 a-110 c each may comprise zincoxide, and the upper contact layers 114 a-114 each may comprise, forexample, Ni, Cr, Ti, and/or an oxide thereof. For instance, as shown inFIG. 3a , the upper contact layers 114 a-114 c each comprise NiTiNbO.The lower contact layers 110 a-110 c and the upper contact layers 114a-114 c sandwich the layers comprising silver 112 a-112 c. The barrierlayers differ as between the FIG. 1 and FIG. 3a examples. In FIG. 3a ,the barrier layers 308 a-308 c, provided below the lower contact layers110 a-110 c, each comprise ZnSnO (although SnO may be used in certainexample instances). The FIG. 3a example also includes an overcoat layer316 comprising zinc oxide.

The following table provides information about the layers in the FIG. 3aexample coated article.

More Preferred Preferred Example Layer Thickness Thickness ThicknessGlass (100) (nm) (nm) (nm) ZnSnO (308a) 10-120 20-100 20 ZnO (110a) 1-203-15 4 Ag (112a) 5-50 10-25  11 NiTiNbO (114a) 1-20 1-10 3 ZnSnO (308b)10-120 30-100 62 ZnO (110b) 1-20 3-15 4 Ag (112b) 5-50 10-25  14 NiTiNbO(114b) 1-20 1-10 3 ZnSnO (308c) 10-120 30-100 67 ZnO (110c) 1-20 3-15 4Ag (112c) 5-50 10-25  17 NiTiNbO (114c) 1-20 1-10 3 ZnO (316) 20-10030-50  38

The layer stack 302 b shown in FIG. 3b is similar to the layer stack 302a shown in FIG. 3a . However, the overcoat layer 316 comprising zincoxide from FIG. 3a is replaced with a two-layer overcoat including alayer comprising ZnSnO 318 and a silicon-inclusive layer 320 (which inthe FIG. 3b example includes silicon oxide, but which may insteadinclude silicon nitride or silicon oxynitride).

The following table provides information about the layers in the FIG. 3bexample coated article.

More Preferred Preferred Example Layer Thickness Thickness ThicknessGlass (100) (nm) (nm) (nm) ZnSnO (308a) 10-120 20-100 34 ZnO (110a) 1-203-15 4 Ag (112a) 5-50 10-25  11 NiTiNbO (114a) 1-20 1-10 3 ZnSnO (308b)10-120 30-100 58 ZnO (110b) 1-20 3-15 4 Ag (112b) 5-50 10-25  13 NiTiNbO(114b) 1-20 1-10 3 ZnSnO (308c) 10-120 30-100 54 ZnO (110c) 1-20 3-15 4Ag (112c) 5-50 10-25  12 NiTiNbO (114c) 1-20 1-10 3 ZnSnO (318) 1-203-15 5 SiOx (320) 20-100 30-50  40

The layer stack 302 c shown in FIG. 3c is similar to the layer stack 302b shown in FIG. 3b , and may be regarded as being the closest to FIG. 1(at least when compared to the other examples shown in and described inconnection with FIGS. 3a-3b ). Compared to FIG. 3b , however, the layerof the overcoat comprising ZnSnO 318 is replaced with a layer 324comprising titanium and/or zirconium. In the FIG. 3c example, this layer324 comprises TiZrOx. The same material is used for the barrier layersin the FIG. 3c example. That is, rather than having barrier layers 308a-308 c comprising ZnSnO or the like as in FIG. 3b , FIG. 3c showsbarrier layers 322 a-322 c comprising TiZrOx.

The following table provides information about the layers in the FIG. 3cexample coated article.

More Preferred Preferred Example Layer Thickness Thickness ThicknessGlass (100) (nm) (nm) (nm) TiZrOx (322a) 10-120 20-100 26 ZnO (110a)1-20 3-15 4 Ag (112a) 5-50 10-25  12 NiTiNbO (114a) 1-20 1-10 3 TiZrOx(322b) 10-120 30-100 51 ZnO (110b) 1-20 3-15 4 Ag (112b) 5-50 10-25  12NiTiNbO (114b) 1-20 1-10 3 TiZrOx (322c) 10-120 30-100 43 ZnO (110c)1-20 3-15 4 Ag (112c) 5-50 10-25  12 NiTiNbO (114c) 1-20 1-10 3 TiZrOx(324) 1-20 3-15 4 SiOx (320) 20-100 30-50  36

FIG. 4 is a graph plotting C vs. LSG values for the example coatedarticles shown in and described in connection with FIGS. 1 and 3 a-3 c.Here, C is color and C=√{square root over ((a*₁−a*₂)²+(b*₁−b*₂)²)}. Ascan be seen from FIG. 4, a triple silver low-E coating including a layercomprising ZnSnOx (corresponding to FIG. 3a ) can be improved upon interms of its C and LSG performance by using layers comprising siliconoxide and zinc stanate (corresponding to FIG. 3b ), and that coating canbe improved upon yet further by using layers comprising silicon oxideand TiZrOx (corresponding to FIG. 3 c). However, none of these tunedlayers provides the combination of C and LSG performance as the FIG. 1example embodiments, which has a metamaterial-inclusive layer. In otherwords, triple silver stacks with one metamaterial layer can achievesuperior LSG without compromising on angular color shift. It thus can beseen that certain example embodiments advantageously additionallyprovide for superior LSG without sacrificing angular coloration.

From a perhaps more basic perspective, five samples were created andtested to compare and contrast the optical performance ofmetamaterial-inclusive layer stacks and more conventional Ag-inclusivelow-E layer stacks. The samples were as follows:

-   -   Sample 1: One 13 nm thick metamaterial layer on 3 mm thick clear        float glass    -   Sample 2: One 10.6 nm thick layer comprising Ag on 3 mm thick        clear float glass    -   Sample 3: 3 mm thick clear float glass/13 nm thick layer        metamaterial layer/10.6 nm thick layer comprising Ag    -   Sample 4: 3 mm thick clear float glass/first layer comprising        silicon nitride (e.g., Si₃N₄) that was 35 nm thick/second layer        comprising silicon nitride (e.g., Si₃N₄) that was 75.1 nm        thick/10.6 nm thick layer comprising Ag/third layer comprising        silicon nitride (e.g., Si₃N₄) that was 15.8 nm thick/layer        comprising silicon oxide (e.g., SiO₂) that was 51.4 nm thick    -   Sample 5: 3 mm thick clear float glass/first layer comprising        silicon nitride (e.g., Si₃N₄) that was 35 nm thick/13 nm thick        layer metamaterial layer/second layer comprising silicon nitride        (e.g., Si₃N₄) that was 75.1 nm thick/10.6 nm thick layer        comprising Ag/third layer comprising silicon nitride (e.g.,        Si₃N₄) that was 15.8 nm thick/layer comprising silicon oxide        (e.g., SiO₂) that was 51.4 nm thick

FIG. 5a plots the transmission, film-side reflectance, and glass-sidereflectance against wavelength for sample 1, and FIG. 5b plots theglass-side a* and b* values against angle for sample 1. As can be seenfrom FIG. 5a , the metamaterial single layer example shows significantchanges for transmission, film-side reflectance, and glass-sidereflectance in the 800-900 nm spectra. However, as can be seen from FIG.5b , the angular coloration is good but could be improved. That is, theglass-side a* and b* values are fairly high and change with viewingangle.

FIG. 6a plots the transmission, film-side reflectance, and glass-sidereflectance against wavelength for sample 2, and FIG. 6b plots theglass-side a* and b* values against angle for sample 2. As can be seenfrom FIG. 6a , there is a continuous change across the whole visiblespectrum and into the NIR region. However, as can be seen from FIG. 6b ,angular coloration is quite poor, particularly with respect to theglass-side a* value being very high and having a significant change fromabout 45 degrees to 90 degrees.

FIG. 7a plots the transmission, film-side reflectance, and glass-sidereflectance against wavelength for sample 3, and FIG. 7b plots theglass-side a* and b* values against angle for sample 3. As can be seenfrom FIG. 7a , the contribution from the metamaterial and the Ag thinfilm is combined, e.g., roughly as if the FIGS. 5a and 5b charts werecombined. However, as can be seen from FIG. 7b , the angular color stillis not good.

As will be appreciated from the description of the samples above,samples 2-3 were improved by adding dielectric layers for optical tuningpurposes. In this regard, FIGS. 8a-8b correspond to FIGS. 6a-6b , exceptthat additional dielectric layers are provided for optical tuning inconnection with sample 4. As will be appreciated from FIGS. 8a-8b ,further tuning is possible through the inclusion of dielectric layers.That is, the transmission is higher in a wider visible wavelength range,and there is a marked improvement in coloration as reflected in FIG. 8b.

FIGS. 9a-9b correspond to FIGS. 7a-7b , except that additionaldielectric layers are provided for optical tuning in connection withsample 5. The addition of dielectric layers helps tune the response yetfurther, maintaining good transmittance over the visible wavelengthrange and also resulting in a much improved film-side reflectance ininfrared spectra starting much earlier compared to FIG. 8a , etc.Moreover, as can be seen from FIG. 9b , angular coloration is excellentonce dielectric spacers are provided. The glass-side a* and b* valuesare both close to each other and extremely close to 0 throughout the0-90 degree viewing angle.

The following table provides optical performance for samples 1-5.

Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Monolithic T Y (%) 67.261.27 37.57 77.77 76.36 Optics a* −3.17 −3.06 −3.53 −2.9 −3.03 (III ‘C’,b* −5.25 −6.67 −13.84 −1.05 −2.47 2 deg obs) Rg Y (%) 12.2 27 39.5 14.54.7 a* 3.57 1.16 0.59 3.59 −0.06 b* 9.29 21.28 21.08 4.75 −1.39 Rf Y (%)17.7 30.6 48.9 12.9 3 a* 4.1 2.46 1.63 5.84 3.45 b* 9.77 18 19.31 14.39−0.93 Tvis (%) 67.2 61.3 37.6 77.8 76.4 Tsol (%) 46.4 41.4 24.2 57.342.1 Rsol (%) 20.4 40.2 39.7 26.1 16 Asol 33.1 18.4 36.1 16.6 41.9 Uval0.596 0.596 0.596 0.596 0.596 SHGC 51.23 43.93 29.45 59.59 48.35 LSG(25)1.312 1.395 1.276 1.305 1.579It can be seen from this table and the description provided above thatoptical color and transmission is not good until the dielectric layerswere provided. Then, it was possible to achieve excellent coloration andLSG values, particularly where an Ag-inclusive layer and a metamateriallayer is provided (i.e., sample 5). It will be appreciated that furthertuning using one or more dielectric layer(s) may be performed in orderto realize yet further improvements in these and/or other regards.

A metamaterial-inclusive layer may include a plurality of island-like orother growths on a substrates in a discontinuous, interrupted stratum orcollection of material. The growths may have different shapes and sizes,and the configurations of the growths play a role in conditioning theoscillating electron cloud and, thus, controlling the resonancefrequency. Geometric parameters that may be optimized include diameteror major distance (d); thickness (t); and interparticle distance (e),which represents the minimum distance between two adjacent particles.Resonance wavelength (in nm) is the wavelength for the minimum intransmittance, and the resonance intensity is the transmittance at theresonance wavelength.

In a related regard, different materials may have different electronicdensities and, thus, cause the resonance to occur at differentwavelengths. For example, Ag, Cu, Al, AZO, Au, RuO₂, ITO, Cr, Ti, andother materials are known to have different extension coefficients andsolar spectral irradiances. Thus, it would be desirable to select aconfiguration for the growth that would be advantageous in terms oflow-E performance and visible light transmission. These materials may beused in connection with, or in place of Ag, in certain exampleembodiments.

Finite-Difference Time-Domain (FDTD) mappings were performed toinvestigate the effects of different metamaterial geometries andmaterials. As is known, FDTD is a numerical analysis technique used formodeling computational electrodynamics. FIGS. 10a-15b are graphsplotting FDTD mapping responses for different metamaterials andconfigurations. More particularly, FIGS. 10a-10b show the resonanceintensity and resonance wavelength for different radius, thickness, andinterparticle distance combinations for columnar Ag metamaterialformations in a silicon oxide matrix. The desired wavelength range hereis the 960.0-1033.3 nm wavelength.

FIG. 11 shows the resonance wavelength for different radius, thickness,and interparticle distance combinations for columnar Ag metamaterialformations in a niobium oxide matrix for columnar Ag metamaterialformations in a silicon oxide matrix. There is a matrix refractive indexeffect on the resonance wavelength. In this case, there is a clearredshift of the resonance when using the higher index NbOx matrixmaterial, e.g., as annotated with the brace in FIG. 11. In a nutshell,it has been found that higher refractive index matrix materials shiftthe resonance towards higher wavelengths.

FIGS. 12a-12b show the resonance intensity and resonance wavelength fordifferent radius, thickness, and interparticle distance combinations forcolumnar Au metamaterial formations in a silicon oxide matrix. As willbe appreciated from a comparison between FIGS. 10a-10b and FIGS. 12a-12b, the FDTD results are nearly identical as between Au and Ag in terms ofboth resonance wavelength and intensity.

FIGS. 13a-13b show the resonance intensity and resonance wavelength fordifferent radius, thickness, and interparticle distance combinations forcolumnar Cu metamaterial formations in a silicon oxide matrix. It willbe appreciated that the Cu has a higher optical absorption in thevisible spectrum, but excellent electronic density and conductivity.Thus, it might sometimes be desirable to use Cu instead of Au and/or Ag,e.g., in view of the more conductive properties of Cu.

FIGS. 14a-14b show the resonance intensity and resonance wavelength fordifferent radius, thickness, and interparticle distance combinations forcolumnar TiN metamaterial formations in a silicon oxide matrix. Here,the position of the resonances is similar to that of Ag and Au. However,the intensity of the resonance is considerably lower. The resonance isalso broader. This suggests that TiN might not be as suitable as theabove-described materials for low-E applications where there is a desirefor high visible transmission, angular color independence, and high LSG,e.g., unless other modifications to a layer stack are made.

FIG. 15 shows the resonance wavelength for different radius, thickness,and interparticle distance combinations for ellipsoidal Ag metamaterialformations in a silicon oxide matrix. In the FIG. 15 example, the radiuscorresponds to the radius along the major diameter, and the thicknesscorresponds to the entirety of the minor diameter. As will beappreciated from FIG. 15, there is a more progressive response whenellipsoids are used, as opposed to cylinders. This may be advantageousin certain example embodiments, as there is a broadening of resonance,e.g., instead of sharp changes as with cylinders. This could, in turn,open up broader processing windows, allow for more variation in radius,thickness, and/or interparticle distance parameters (which may bedifficult to precisely control in some instances), etc.

It will be appreciated that the silicon oxide inclusive matrix maycomprise or consist essentially of SiO₂ in certain example embodiments.In certain example embodiments, any silicon or niobium inclusive matrixmay be used, and further details are provided below in this regard. Asalluded to above, it will be appreciated that Ag, Cu, Al, AZO, Au, RuO₂,ITO, and/or other metamaterials may be used in certain exampleembodiments.

Semiconductor, transparent conductive oxide (TCO), and other materialsmay be used in different example embodiments. Thus, although certainexample embodiments have been described in connection with Ag-inclusivemetamaterial layers, it will be appreciated that other materials may beused in place of or together with Ag-based metal island layers. Othercandidate materials that may be used in place of or together with Aginclude so-called noble metals. In addition, materials such as Al, Au,AZO, Be, C, Cr, Cu, ITO, Ni, Pd, Pt, RuO₂, Ti, and/or W may be used incertain example embodiments.

Tests were performed to determine how metamaterial-inclusive layerscould be self-assembled. In this regard, matrix materials were sputterdeposited on a glass substrate above and below a sputter deposited layerof metal, and the intermediate article was heat treated. In a first setof experiments, self-assembled metamaterials were created by depositinga layer comprising Ag between two layers comprising NbOx deposited inthe metallic state. The layer comprising Ag was deposited with a lowline speed and high power, i.e., at a line speed of 8 m/min and at apower of 12 kW. The layers comprising NbOx were sputter deposited at 1.2m/min. The coating was designed to have the same as-deposited thicknessfor the two layers comprising NbOx, namely, 30 nm thicknesses, and tohave an 8 nm thickness for the layer comprising Ag. As shown in the FIG.17a TEM images, however, the lower layer comprising NbOx, as deposited,was about 50 nm thick and the upper layer comprising NbOx, as deposited,was about 60 nm thick.

FIG. 16 is a graph showing the plasmon resonance observed in thecalculated absorption from optical measurements for different heattreatment temperature and times for this first set of experiments. Ascan be seen from FIG. 16, samples heat treated at the higher temperature(650 degrees C.) show better performance than those samples heat treatedat the lower temperature (350 degrees C.), and samples heat treated forlonger periods of time show better performance than those samples heattreated for shorter periods of time. With respect to the samples heattreated 650 degrees C., the sample heat treated for 8 minutes shows thebeginnings of resonance in the NIR wavelength range while absorption inthe visible wavelength range remains low; the sample heat treated for 10minutes shows the broadening of the resonance; the sample heat treatedfor 16 minutes produces a more defined resonance, and the sample heattreated for 20 minutes shows a further intensification of the resonance.

FIG. 17a is a TEM image showing the as-deposited layer stack, FIG. 17bis a TEM image showing the evolution of the layer stack after an 8minute heat treatment at 650 degrees C., and FIG. 17c is a TEM imageshowing the further evolution of the layer stack after a 20 minute heattreatment at 650 degrees C. As can be seen from FIG. 17c , after thisheat treatment regime and with this layer stack, the Ag coalesced andformed spheroidal-shaped particles that were self-assembled in thecenter layer of the stack. Some small, randomly-shaped particles alsoare visible. The self-assembly is believed to be facilitated by virtueof the mismatch in surface energy as between the major surfaces of thelayer comprising Ag, the upper surface of the lower layer comprisingNbOx, and the lower surface of the upper layer comprising NbOx.

In a second set of experiments, self-assembled metamaterials werecreated by depositing a layer comprising Ag between two layerscomprising NbOx deposited in the metallic state, but the speed and powerof the deposition were changed. That is, the layer comprising Ag wasdeposited with a high line speed and lower power, i.e., at a line speedof 10 m/min. The layers comprising NbOx again were sputter deposited at1.2 m/min.

FIG. 18 is similar to FIG. 16, in that FIG. 18 is a graph showing theplasmon resonance observed in the calculated absorption from opticalmeasurements for different heat treatment temperature and times for thissecond set of experiments. As above, samples in this set were heattreated at low and high temperatures (350 degrees C. and 650 degrees C.,respectively), and for different lengths of time (namely, 8, 10, 16, and20 minutes). However, as will be appreciated from FIG. 18, there is noreal apparent resonance observed in any of the samples.

The lack of apparent resonance likely was because the particle size wastoo small in this set of samples. The TEM images in FIGS. 19a-19c seemto confirm this view. That is, FIG. 19a is a TEM image showing theas-deposited layer stack, FIG. 19b is a TEM image showing the evolutionof the layer stack after an 8 minute heat treatment at 650 degrees C.,and FIG. 19c is a TEM image showing the further evolution of the layerstack after a 20 minute heat treatment at 650 degrees C. As can be seenfrom FIGS. 19a-19c , after this heat treatment regime and with thislayer stack, the samples exhibited small, randomly distributedparticles. Whereas the first set of examples showed good densification,possibly enabled from the low line speed/high power depositiontechnique, the non-uniformities in the second set of samples resulted in“fluffy” as-deposited layers and led to the distribution of smallparticles throughout a big, thick layer. In the latter case, thishampered the development of the ultimate metamaterial-inclusive layer.In general, when it comes to silver deposition for this purpose, powerlevels in the 10-100 kW range, more preferably 10-75 kW range, and stillmore preferably 10-50 kW range, may be used in connection with certainexample embodiments. Line speeds less than 20 m/min. are preferable whenit comes to silver deposition for this purpose, with speeds less than 15m/min. being preferred and speeds in the 5-15 m/min. being morepreferred.

These results are interesting, as it was expected that there would bemore adatom growth and that that would be a dominant growth regime.Surprisingly and unexpectedly, however, surface tensions seemed to havea significant influence on spherical agglomeration. Thus, in certainexample embodiments, materials may be carefully selected so as to havesurface tensions that work well with the silver or material used in themetamaterial creation. Oxides of Nb and/or Si have been found to beadvantageous in this regard. It has been found that it is preferable toform the matrix holding the material by forming a first amount of matrixmaterial, applying the silver or material used in the metamaterialcreation, and applying a second amount of matrix material, and thensubjecting this layer stack to heat treatment to trigger self-assemblyof the metamaterial-inclusive layer. Preferably, the as-depositedthicknesses of the matrix material above and below application of thesilver or material used in the metamaterial creation each are 10-300 nmand more preferably 10-100 nm, still more preferably 30-70 nm, withexample thicknesses being in 30 nm, 50 nm, and 60 nm. Preferably, theas-deposited thicknesses of the matrix material before and afterapplication of the silver or material used in the metamaterial creationare substantially equal. That is, the as-deposited thicknesses of thematrix material before and after application of the silver or materialused in the metamaterial creation preferably differ from one another byno more than 20%, more preferably no more than 15%, and sometimes nomore than 5-10%. The thickness of the silver or material used in themetamaterial creation may be from 1-20 nm, more preferably 1-15 nm, andstill more preferably 5-10 nm, e.g., with an example of 8 nm. It will beappreciated that the latter of such thicknesses may be determined inconnection with the interparticle spacing and diameters or majordistance, e.g., as informed by the discussion above in connection withFIGS. 10a -15. In general, interparticle distances of 5-75 nm, diametersor major distances of 20-140 nm, and thicknesses of 5-50 nm or 10-50 nmmay be used in different example embodiments.

Heating involved in the self-assembly may be performed at a temperatureof 580-700 degrees C., more preferably 600-675 degrees C., and stillmore preferably 625-650 degrees C. The heating may be performed for 1-60minutes, more preferably 10-30 minutes, and still more preferably 15-30or 15-25 minutes, with an example time being at least 20 minutes.

It will be appreciated that the layers discussed herein may be formed inany suitable way. For example, a physical vapor deposition (PVD)technique such as sputtering or the like may be used to form the layers,as well as the metal or other islands that may be self-assembled intometamaterial inclusive layers in certain example embodiments.Metamaterials also may be formed via nano-imprinting, roll-to-rolltransfers, evaporation on a micro-scale, etc.

Certain example embodiments may have metal island layers or formationsuseful in the metamaterial-inclusive layers discussed herein may beformed in accordance with the techniques of U.S. application Ser. No.15/051,900 and/or U.S. application Ser. No. 15/051,927, each filed onFeb. 24, 2016, the entire contents of each of which is herebyincorporated by reference herein.

Furthermore, although certain example embodiments have been described asproviding metamaterial-inclusive layers and/or layer stacks that providesubstantially constant color as a function of angle, it will beappreciated that other optical and/or other behaviors may be provided inplace of, or together with, substantially constant color vs. angle. Forexample, depending on the type of material selected, the size of theislands formed, etc., it may be possible to achieve desired color shifts(e.g., that are substantially constant across viewing angles) via largea* and/or b* changes; high conductivity or high resistivity; highreflection (e.g., for a mirror or mirror-like application); creation ofcolored transmission to simulate a tinted substrate (e.g., consistentlyacross a wide range of viewing angles); creation of color or visualacuity enhancing effects such as might be used with sunglasses whereparticular visible ranges of wavelengths are selectively absorbed; etc.

The terms “heat treatment” and “heat treating” as used herein meanheating the article to a temperature sufficient to achieve thermaltempering and/or heat strengthening of the glass inclusive article. Thisdefinition includes, for example, heating a coated article in an oven orfurnace at a temperature of at least about 550 degrees C., morepreferably at least about 580 degrees C., more preferably at least about600 degrees C., more preferably at least about 620 degrees C., and mostpreferably at least about 650 degrees C. for a sufficient period toallow tempering and/or heat strengthening. This may be for at leastabout two minutes, or up to about 10 minutes, in certain exampleembodiments. These processes may be adapted to involve different timesand/or temperatures, e.g., to work with the self-assembling approachesto metamaterial-inclusive layer formation described herein.

As used herein, the terms “on,” “supported by,” and the like should notbe interpreted to mean that two elements are directly adjacent to oneanother unless explicitly stated. In other words, a first layer may besaid to be “on” or “supported by” a second layer, even if there are oneor more layers therebetween.

In certain example embodiments, a method of making a coated articlecomprising a low-E coating supported by a glass substrate is provided.The method comprises: forming a first matrix layer comprising a matrixmaterial, directly or indirectly on the substrate; forming a donor layercomprising Ag over and contacting the first matrix layer; followingformation of the donor layer, forming a second matrix layer comprisingthe matrix material over and contacting the donor layer, wherein thefirst and second matrix layers have thicknesses differing from oneanother by no more than 20%; heat treating the coated article with atleast the first and second matrix layers and the donor layer thereon tocause the Ag in the donor layer to self-assemble into a discontinuouscollection of formations distributed in the matrix material in forming ametamaterial inclusive layer that emits resonances in a desiredwavelength range based at least in part on the formations locatedtherein; and incorporating the metamaterial inclusive layer into thelow-E coating.

In addition to the features of the previous paragraph, in certainexample embodiments, the heat treating may be performed for 15-30minutes and/or at 600-675 degrees C.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the first and second matrix layers each mayhave an as-deposited thickness of 30-70 nm.

In addition to the features of any of the three previous paragraphs, incertain example embodiments, the matrix material may comprise Nb and/orSi (e.g., the matrix material may comprise niobium oxide).

In addition to the features of any of the four previous paragraphs, incertain example embodiments, the donor layer may have an as-depositedthickness of 5-10 nm.

In addition to the features of any of the five previous paragraphs, incertain example embodiments, the formations may be formed to have aninterparticle spacing of 5-75 nm and diameters or major distances of20-140 nm.

In addition to the features of any of the six previous paragraphs, incertain example embodiments, the formations may be formed to have 10-50nm thicknesses.

In addition to the features of any of the seven previous paragraphs, incertain example embodiments, the formations may be substantiallyellipsoidal.

In addition to the features of any of the eight previous paragraphs, incertain example embodiments, the donor layer may be formed by sputterdeposition performed at a power level of 10-50 kW and at a line speed of5-15 m/min.

In addition to the features of any of the nine previous paragraphs, incertain example embodiments, a plurality of continuous and uninterruptedIR reflecting layers may be formed, with each IR reflecting layercomprising Ag.

In addition to the features of the previous paragraph, in certainexample embodiments, a plurality of barrier layers comprising TiZrOx maybe formed.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the IR reflecting layers may be formed overthe metamaterial inclusive layer on a side of the metamaterial inclusivelayer opposite the substrate.

In addition to the features of any of the three previous paragraphs, incertain example embodiments, the heat treating may be performedfollowing formation of the IR reflecting layers.

In certain example embodiments, a method of making a coated articlecomprising a low-E coating supported by a glass substrate is provided.The method comprises: forming a first matrix layer comprising a matrixmaterial, directly or indirectly on the substrate; forming a continuousand uninterrupted donor layer over and contacting the first matrixlayer, with the donor layer comprising one or more source material(s)selected from the group consisting of: Ag, Al, Au, AZO, Be, C, Cr, Cu,ITO, Ni, Pd, Pt, RuO2, Ti, and W; and following formation of the donorlayer, forming a second matrix layer comprising the matrix material overand contacting the donor layer, wherein the first and second matrixlayers have thicknesses differing from one another by no more than 20%.The coated article with at least the first and second matrix layers andthe donor layer thereon are heat treatable to cause the sourcematerial(s) in the donor layer to self-assemble into a synthetic layercomprising a discontinuous collection of formations distributed in thematrix material, with the formations having a major distance no largerthan 300 nm, and with the synthetic layer having resonance in afrequency range suitable for the low-E coating.

In addition to the features of the previous paragraph, in certainexample embodiments, the first and second matrix layers each may have anas-deposited thickness of 30-70 nm.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the matrix material may comprise an oxideof Nb and/or Si.

In addition to the features of any of the three previous paragraphs, incertain example embodiments, the donor layer may have an as-depositedthickness of 5-10 nm.

In addition to the features of any of the four previous paragraphs, incertain example embodiments, the heat treating may be performable at atime and at a temperature sufficient to cause the formations to have aninterparticle spacing of 5-75 nm and diameters or major distances of20-140 nm.

In addition to the features of any of the five previous paragraphs, incertain example embodiments, the heat treating may be performable at atime and at a temperature sufficient to cause the formations to have10-50 nm thicknesses.

In addition to the features of any of the six previous paragraphs, incertain example embodiments, the donor layer may be formed by sputterdeposition performed at a power level of 10-50 kW and at a line speed of5-15 m/min.

In addition to the features of any of the seven previous paragraphs, incertain example embodiments, a plurality of continuous and uninterruptedIR reflecting layers may be formed, with each IR reflecting layercomprising Ag.

In addition to the features of the previous paragraph, in certainexample embodiments, a plurality of barrier layers comprising TiZrOx maybe formed.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the IR reflecting layers may be formed overthe synthetic layer on a side of the synthetic layer opposite thesubstrate, following heat treatment.

In addition to the features of any of the three previous paragraphs, incertain example embodiments, the IR reflecting layers are formed overthe second matrix layer, prior to heat treatment.

In certain example embodiments, a method of making a coated articlecomprising a low-E coating supported by a glass substrate is provided.The method comprises: having a plurality of layers formed on thesubstrate, the layers including: (a) a first matrix layer comprising amatrix material, directly or indirectly on the substrate, (b) a donorlayer comprising Ag over and contacting the first matrix layer, and (c)a second matrix layer comprising the matrix material over and contactingthe donor layer, wherein the first and second matrix layers havethicknesses differing from one another by no more than 20%; and heattreating the coated article with at least the first and second matrixlayers and the donor layer thereon to cause the Ag in the donor layer toself-assemble into a discontinuous collection of formations distributedin the matrix material in forming a metamaterial inclusive layer, withthe metamaterial inclusive layer having resonance in a selectedfrequency range suitable for the low-E coating.

In addition to the features of the previous paragraph, in certainexample embodiments, the heat treating may be performed for 15-30minutes and/or at 600-675 degrees C.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the first and second matrix layers each mayhave an as-deposited thickness of 30-70 nm.

In addition to the features of any of the three previous paragraphs, incertain example embodiments, the matrix material may comprise an oxideof Nb and/or Si.

In addition to the features of any of the four previous paragraphs, incertain example embodiments, the heat treating may be performed at atime and at a temperature sufficient to cause the formations to have aninterparticle spacing of 5-75 nm and diameters or major distances of20-140 nm.

In addition to the features of any of the five previous paragraphs, incertain example embodiments, the heat treating may be performed at atime and at a temperature sufficient to cause the formations to have10-50 nm thicknesses.

In addition to the features of any of the six previous paragraphs, incertain example embodiments, a plurality of continuous and uninterruptedIR reflecting layers may be formed, with each IR reflecting layercomprising Ag.

In addition to the features of the previous paragraph, in certainexample embodiments, a plurality of barrier layers comprising TiZrOx maybe formed.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the IR reflecting layers may be formed overthe metamaterial inclusive layer on a side of the metamaterial inclusivelayer opposite the substrate, following heat treatment.

In addition to the features of any of the three previous paragraphs, incertain example embodiments, the IR reflecting layers may be formed overthe second matrix layer, prior to heat treatment.

In certain example embodiments, there is provided an intermediatearticle, comprising a glass substrate. A first matrix layer comprising amatrix material is located directly or indirectly on the substrate. Adonor layer comprising Ag is located over and contacting the firstmatrix layer. A second matrix layer comprising the matrix material islocated over and contacting the donor layer. The first and second matrixlayers have thicknesses differing from one another by no more than 20%.The intermediate article is heat treatable with at least the first andsecond matrix layers and the donor layer thereon to cause the Ag in thedonor layer to self-assemble into a discontinuous collection offormations distributed in the matrix material in forming a metamaterialinclusive layer that emits resonances in a desired wavelength rangebased at least in part on the formations located therein.

In addition to the features of the previous paragraph, in certainexample embodiments, the first and second matrix layers each may have anas-deposited thickness of 30-70 nm.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the matrix material may comprise Nb and/orSi (e.g., the matrix material may comprise niobium oxide).

In addition to the features of any of the three previous paragraphs, incertain example embodiments, the donor layer may have an as-depositedthickness of 5-10 nm.

In addition to the features of any of the four previous paragraphs, incertain example embodiments, the heat treating may be performable at atime and temperature sufficient to cause the formations to have aninterparticle spacing of 5-75 nm and diameters or major distances of20-140 nm.

In addition to the features of any of the five previous paragraphs, incertain example embodiments, the heat treating may be performable at atime and temperature sufficient to cause the formations to have 10-50 nmthicknesses.

In addition to the features of any of the six previous paragraphs, incertain example embodiments, a plurality of continuous and uninterruptedIR reflecting layers may be provided, with each IR reflecting layercomprising Ag.

In addition to the features of the previous paragraph, in certainexample embodiments, a plurality of barrier layers comprising TiZrOx maybe provided.

In addition to the features of either of the two previous paragraphs, incertain example embodiments, the IR reflecting layers may be formed overthe metamaterial inclusive layer on a side of the metamaterial inclusivelayer opposite the substrate.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A method of making a coated article comprising alow-E coating supported by a glass substrate, the method comprising:forming a first matrix layer comprising a matrix material, directly orindirectly on the substrate; forming a donor layer comprising Ag overand contacting the first matrix layer; following formation of the donorlayer, forming a second matrix layer comprising the matrix material overand contacting the donor layer, wherein the first and second matrixlayers have thicknesses differing from one another by no more than 20%;heat treating the coated article with at least the first and secondmatrix layers and the donor layer thereon to cause the Ag in the donorlayer to self-assemble into a discontinuous collection of formationsdistributed in the matrix material in forming a metamaterial inclusivelayer that emits resonances in a desired wavelength range based at leastin part on the formations located therein; and incorporating themetamaterial inclusive layer into the low-E coating.
 2. The method ofclaim 1, wherein the heat treating is performed for 15-30 minutes. 3.The method of claim 2, wherein the heat treating is performed at 600-675degrees C.
 4. The method of claim 1, wherein the heat treating isperformed at 600-675 degrees C.
 5. The method of claim 1, wherein thefirst and second matrix layers each have an as-deposited thickness of30-70 nm.
 6. The method of claim 1, wherein the matrix materialcomprises Nb and/or Si.
 7. The method of claim 6, wherein the matrixmaterial comprises niobium oxide.
 8. The method of claim 1, wherein thedonor layer has an as-deposited thickness of 5-10 nm.
 9. The method ofclaim 1, wherein the formations are formed to have an interparticlespacing of 5-75 nm and diameters or major distances of 20-140 nm. 10.The method of claim 9, wherein the formations are formed to have 10-50nm thicknesses.
 11. The method of claim 1, wherein the formations aresubstantially ellipsoidal.
 12. The method of claim 1, wherein the donorlayer is formed by sputter deposition performed at a power level of10-50 kW and at a line speed of 5-15 m/min.
 13. The method of claim 1,further comprising forming a plurality of continuous and uninterruptedIR reflecting layers, each IR reflecting layer comprising Ag.
 14. Themethod of claim 13, further comprising forming a plurality of barrierlayers comprising TiZrOx.
 15. The method of claim 13, wherein the IRreflecting layers are formed over the metamaterial inclusive layer on aside of the metamaterial inclusive layer opposite the substrate.
 16. Themethod of claim 13, wherein the heat treating is performed followingformation of the IR reflecting layers.
 17. A method of making a coatedarticle comprising a low-E coating supported by a glass substrate, themethod comprising: forming a first matrix layer comprising a matrixmaterial, directly or indirectly on the substrate; forming a continuousand uninterrupted donor layer over and contacting the first matrixlayer, the donor layer comprising one or more source material(s)selected from the group consisting of: Ag, Al, Au, AZO, Be, C, Cr, Cu,ITO, Ni, Pd, Pt, RuO2, Ti, and W; and following formation of the donorlayer, forming a second matrix layer comprising the matrix material overand contacting the donor layer, wherein the first and second matrixlayers have thicknesses differing from one another by no more than 20%;wherein the coated article with at least the first and second matrixlayers and the donor layer thereon are heat treatable to cause thesource material(s) in the donor layer to self-assemble into a syntheticlayer comprising a discontinuous collection of formations distributed inthe matrix material, the formations having a major distance no largerthan 300 nm, the synthetic layer having resonance in a frequency rangesuitable for the low-E coating.
 18. The method of claim 17, wherein thefirst and second matrix layers each have an as-deposited thickness of30-70 nm.
 19. The method of claim 17, wherein the matrix materialcomprises an oxide of Nb and/or Si.
 20. The method of claim 17, whereinthe donor layer has an as-deposited thickness of 5-10 nm.
 21. The methodof claim 17, wherein the heat treating is performable at a time and at atemperature sufficient to cause the formations to have an interparticlespacing of 5-75 nm and diameters or major distances of 20-140 nm. 22.The method of claim 21, wherein the heat treating is performable at atime and at a temperature sufficient to cause the formations to have10-50 nm thicknesses.
 23. The method of claim 17, wherein the donorlayer is formed by sputter deposition performed at a power level of10-50 kW and at a line speed of 5-15 m/min.
 24. The method of claim 17,further comprising forming a plurality of continuous and uninterruptedIR reflecting layers, each IR reflecting layer comprising Ag.
 25. Themethod of claim 24, further comprising forming a plurality of barrierlayers comprising TiZrOx.
 26. The method of claim 24, wherein the IRreflecting layers are formed over the synthetic layer on a side of thesynthetic layer opposite the substrate, following heat treatment. 27.The method of claim 24, wherein the IR reflecting layers are formed overthe second matrix layer, prior to heat treatment.
 28. A method of makinga coated article comprising a low-E coating supported by a glasssubstrate, the method comprising: having a plurality of layers formed onthe substrate, the layers including: (a) a first matrix layer comprisinga matrix material, directly or indirectly on the substrate, (b) a donorlayer comprising Ag over and contacting the first matrix layer, and (c)a second matrix layer comprising the matrix material over and contactingthe donor layer, wherein the first and second matrix layers havethicknesses differing from one another by no more than 20%; and heattreating the coated article with at least the first and second matrixlayers and the donor layer thereon to cause the Ag in the donor layer toself-assemble into a discontinuous collection of formations distributedin the matrix material in forming a metamaterial inclusive layer, themetamaterial inclusive layer having resonance in a selected frequencyrange suitable for the low-E coating.
 29. The method of claim 28,wherein the heat treating is performed for 15-30 minutes.
 30. The methodof claim 29, wherein the heat treating is performed at 600-675 degreesC.
 31. The method of claim 28, wherein the heat treating is performed at600-675 degrees C.
 32. The method of claim 28, wherein the first andsecond matrix layers each have an as-deposited thickness of 30-70 nm.33. The method of claim 28, wherein the matrix material comprises anoxide of Nb and/or Si.
 34. The method of claim 28, wherein the heattreating is performed at a time and at a temperature sufficient to causethe formations to have an interparticle spacing of 5-75 nm and diametersor major distances of 20-140 nm.
 35. The method of claim 34, wherein theheat treating is performed at a time and at a temperature sufficient tocause the formations to have 10-50 nm thicknesses.
 36. The method ofclaim 28, further comprising forming a plurality of continuous anduninterrupted IR reflecting layers, each IR reflecting layer comprisingAg.
 37. The method of claim 36, further comprising forming a pluralityof barrier layers comprising TiZrOx.
 38. The method of claim 36, whereinthe IR reflecting layers are formed over the metamaterial inclusivelayer on a side of the metamaterial inclusive layer opposite thesubstrate, following heat treatment.
 39. The method of claim 36, whereinthe IR reflecting layers are formed over the second matrix layer, priorto heat treatment.
 40. An intermediate article, comprising: a glasssubstrate; a first matrix layer comprising a matrix material, locateddirectly or indirectly on the substrate; a donor layer comprising Aglocated over and contacting the first matrix layer; and a second matrixlayer comprising the matrix material located over and contacting thedonor layer, wherein the first and second matrix layers have thicknessesdiffering from one another by no more than 20%; wherein the intermediatearticle is heat treatable with at least the first and second matrixlayers and the donor layer thereon to cause the Ag in the donor layer toself-assemble into a discontinuous collection of formations distributedin the matrix material in forming a metamaterial inclusive layer thatemits resonances in a desired wavelength range based at least in part onthe formations located therein.
 41. The article of claim 40, wherein thefirst and second matrix layers each have an as-deposited thickness of30-70 nm.
 42. The article of claim 40, the matrix material comprises Nband/or Si.
 43. The article of claim 42, wherein the matrix materialcomprises niobium oxide.
 44. The article of claim 40, wherein the donorlayer has an as-deposited thickness of 5-10 nm.
 45. The article of claim40, wherein the heat treating is performable at a time and temperaturesufficient to cause the formations to have an interparticle spacing of5-75 nm and diameters or major distances of 20-140 nm.
 46. The articleof claim 45, wherein the heat treating is performable at a time andtemperature sufficient to cause the formations to have 10-50 nmthicknesses.
 47. The article of claim 40, further comprising a pluralityof continuous and uninterrupted IR reflecting layers, each IR reflectinglayer comprising Ag.
 48. The article of claim 47, further comprising aplurality of barrier layers comprising TiZrOx.
 49. The article of claim47, wherein the IR reflecting layers are formed over the metamaterialinclusive layer on a side of the metamaterial inclusive layer oppositethe substrate.